Causes of corrosion of fine copper wires carrying a potential

COPPER CORROSION is a serious problem in electrical equipment which uses very fine wires carrying a potential, the outstanding examples being various types of coils used in radios and ignition systems. The usual type of corrosion involves the formation of green material on the surface of the wire, which is obviously due to chemical reaction of the copper with materials in contact with it. As this chemical reaction progresses at a given point in the wire, the cross section of unchanged copper gradually diminishes until finally a break occurs, opening the circuit and rendering the coil useless.